Why are my teeth yellow? Causes and what helps

A tooth is not paper white

A tooth’s color starts on the inside. Enamel, the outer layer, is partly translucent; underneath, the dentin is yellowish. What you see in the mirror blends the two. According to Cleveland Clinic, tooth color varies widely from person to person, and teeth that differ in color from someone else’s don’t mean something is wrong.

Pigments from outside can add to that natural color. The American Dental Association (ADA) separates two kinds: extrinsic stains, which sit on the enamel surface, and intrinsic stains, which come from the tooth itself. They don’t respond to the same products, so knowing which one you’re looking at keeps you from buying the wrong one.

References: [1] ADA · [2] Cleveland Clinic

What color are natural teeth?

There is no single normal color. A study measured the upper front teeth of 1,361 Spanish adults aged 16 to 89 with a spectrophotometer, and lightness ranged widely from one person to the next. On average, teeth were a little less light and more yellow with each year of age, and women’s teeth were slightly lighter and less yellow than men’s. The study did not look at coffee, tobacco or other habits.

Codes such as A1, A2 or A3 come from a dentist’s shade guide, matched by eye against the tooth under suitable light; a photo or a chart on a screen can’t give you one. In Enamel, your index is a position on the app’s own scale, read against your own earlier scans, and no position is the “normal” one.

References: [2] Cleveland Clinic · [8] Gómez Polo et al.

Coffee, tea, wine, tobacco: surface stains

According to the ADA, extrinsic stains come from pigments building up on enamel: tobacco, strongly colored drinks such as coffee, tea, red wine or cola, and dark foods such as berries. Cleveland Clinic adds soy sauce. One cup doesn’t show; it’s the repetition, day after day, that does.

The habits that help are simple. Cleveland Clinic advises drinking water and rinsing your mouth after a drink that stains, brushing at least twice a day and not skipping routine cleanings and exams at the dentist. You don’t have to give up coffee.

References: [1] ADA · [2] Cleveland Clinic

With age, the shade deepens a little

Even without coffee, the shade changes. According to the ADA, enamel becomes thinner and more translucent with age, which lets more of the yellower dentin show through. Cleveland Clinic describes the same process.

This is an intrinsic change: not a stain you can scrub off. The ADA notes that whitening toothpastes work mainly on surface stains and don’t have a significant effect on intrinsic ones. To lighten the tooth’s own color, it takes a peroxide product.

References: [1] ADA · [2] Cleveland Clinic · [3] ADA

Light can make a smile look yellow too

Some of the yellow you see may come from the room rather than your teeth. Under a warm bulb, the same smile looks yellower; by a window, whiter. A pilot study in dental photography observed shade differences depending on the light source used, and every phone adjusts the colors of its photos its own way.

Before concluding that your teeth have turned yellow, look at where and how you saw them. Two photos taken in different rooms are not enough to show a change.

References: [7] Pundir et al.

What helps, depending on the cause

The right answer depends on what you’re looking at. Whitening toothpaste works on the surface. According to the UFSBD, the French association for oral health, it contains more polishing agents, and the larger their particles, the more abrasive it is: ask your dentist, especially if your teeth are sensitive.

For the tooth’s own color, it takes a peroxide product: strips, trays or in-office sessions. In the European Union, over-the-counter products contain no more than 0.1% hydrogen peroxide; between 0.1% and 6%, they are supplied only through dentists. Products sold elsewhere do not necessarily follow these limits; in the United States, follow the instructions on the box. These products only lighten natural teeth: a crown or veneer keeps its color.

When whitening isn’t enough, the UFSBD mentions veneers, thin shells placed on the visible side of the front teeth: a cosmetic treatment to discuss with a dentist.

References: [1] ADA · [4] UFSBD · [5] UFSBD · [6] Règlement (UE) 344/2013

When to ask a dentist

Some discoloration isn’t a job for a whitening product: a single tooth getting darker, a sudden change, a gray or brown shade present since childhood, for example after certain antibiotics taken as a child, or a child’s teeth changing color. That’s one for a dentist to look at.

And before starting any whitening, the ADA recommends asking a dentist whether it suits you, especially if you have crowns or veneers on your front teeth.

References: [1] ADA · [2] Cleveland Clinic